It is known in the biological diagnostic assay field to utilize conjugates of biologically active moieties with a detectable, signal-generating dye moiety which may be, for example, a moiety which emits electromagnetic radiation, e.g., a fluorescent, chemiluminescent or bioluminescent moiety. The biologically active moiety may be: a DNA probe, e.g., a labeled DNA probe of the type used in detecting complementary DNA sequences; an enzyme; an enzyme inhibitor; an antigen; an antibody; a hapten, etc.
In recent years much attention has been focused on labeled-reagent immunoassays for the detection of body fluid components such as antigens, hormones, infectious agents, serum antibodies and the like. Consequently, the patent literature includes many disclosures of various assays involving a labeled-reagent reaction between antigens and antibodies to provide a detectable signal which may be a change in color, emission of electromagnetic radiation, etc. These assays involve an immunological interaction between a ligand and an antiligand wherein at least one of the two reactants contains a substance or a precursor of a substance which can provide the detectable signal as a function of the immunological ligand-antiligand interaction.
One class of labels commonly used in such assays are fluorescent dyes or fluorophores. Both heterogeneous and homogeneous specific binding assays employing fluorescent-labeled conjugates are well known in the art. In general, it is desirable that fluorescent labels for use in such assays have a relatively long emission wavelength, e.g., above 500 mm. In addition, it is desirable that the labels have a large Stokes shift, be stable under the assay conditions, be relatively free of non-specific interference both from materials in solution and the moiety to which the label is conjugated and provide high quantum yields.
The present invention relates to novel fluorescent conjugates comprising a rhodamine dye moiety linked to a biologically active moiety and their use in biological diagnostic assay elements and processes.
It is therefore an object of this invention to provide novel fluorescent conjugates which include a biologically active moiety and a fluorescent dye moiety.
A further object is to provide biological diagnostic assay elements and processes.